The cases are presented in random order, and the judges spend little time on each one, an average of 6 minutes. (The default decision is denial of parole; only 35% of requests are approved. The exact time of each decision is recorded, and the times of the judges three food breaksmorning break, lunch, and afternoon breakduring the day are recorded as well.) The authors of the study plotted the proportion of approved requests against the time since the last food break. The proportion spikes after each meal, when about 65% of requests are granted. During the two hours or so until the judges next feeding, the approval rate drops steadily, to about zero just before the meal. As you might expect, this is an unwelcome result and the authors carefully checked many alternative explanations. The best possible account of the data provides bad news: tired and hungry judges tend to fall back on the easier default position of denying requests for parole. Both fatigue and hunger probably play a role.

The Lazy System 2 One of the main functions of System 2 is to monitor and control thoughts and actions suggested by System 1, allowing some to be expressed directly in behavior and suppressing or modifying others. For an example, here is a simple puzzle. Do not try to solve it but listen to your intuition: A bat and ball cost $1.10. The bat costs one dollar more than the ball. How much does the ball cost? A number came to your mind. The number, of course, is 10: 10. The distinctive mark of this easy puzzle is that it evokes an answer that is intuitive, appealing, and wrong. Do the math, and you will see. If the ball costs 10, then the total cost will be $1.20 (10 for the ball and $1.10 for the bat), not $1.10. The correct answer is 5. It%">5. is safe to assume that the intuitive answer also came to the mind of those who ended up with the correct numberthey somehow managed to resist the intuition. Shane Frederick and I worked together on a theory of judgment based on two systems, and h

His reasoning was that we know a significant fact about anyone who says that the ball costs 10: that person did not actively check whether the answer was correct, and her System 2 endorsed an intuitive answer that it could have rejected with a small investment of effort. Furthermore, we also know that the people who give the intuitive answer have missed an obvious social cue; they should have wondered why anyone would include in a questionnaire a puzzle with such an obvious answer. A failure to check is remarkable because the cost of checking is so low: a few seconds of mental work (the problem is moderately difficult), with slightly tensed muscles and dilated pupils, could avoid an embarrassing mistake. People who say 10 appear to be ardent followers of the law of least effort. People who avoid that answer appear to have more active minds. Many thousands of univer

More than 50% of students at Harvard, MIT, and Princeton ton gave the intuitiveincorrectanswer. At less selective universities, the rate of demonstrable failure to check was in excess of 80%. The bat-and-ball problem is our first encounter with an observation